This invention relates to spark gap assemblies for voltage surge arresters such as lightning arresters.
In voltage surge suppressors, such as lightning arresters, there is usually a spark gap assembly containing a number of pairs of electrodes for producing a discharge current path upon occurrence of a predetermined overvoltage. One such assembly is that disclosed in U.S. Pat. No. 3,504,221, Mar. 31, 1970, by the present applicant. In the assembly of the prior patent, a stack of insulating plates is used with the opposing surfaces of the plates each bearing a single electrode for defining a spark gap between that electrode and an electrode mounted on the adjacent surface of an adjacent insulating plate. In order to define the spark gap between the two electrodes, which are physically mounted to separate insulating plates, it was necessary to apply a gauge through an external aperture in the adjacent plates extending through the locus between the electrodes and to rotate the plates relative to each other until the prescribed gap spacing was achieved, then after removing the gauge to secure the plates into a structural unit in which the gap was intended to remain the same. This structure and technique have been successfully used and the operability of arresters employing them has been satisfactory.
There is now increasing emphasis on providing spark gap assemblies that can not only be made reliably and with proper operating characteristics but which can be so made with greater economy and ease of fabrication. In the latter respect it has been considered undesirable to employ an adjustable spark gap as provided in the above-mentioned patent.
Another patent mentioned by way of further background for a spark gap assembly is 3,069,589, Dec. 18, 1962. In the latter patent the spark gap electrodes are formed of embossed areas upon a conductive plate disposed between adjacent insulating plates through which there are apertures so as to define a gap between electrodes on different sides of such an insulating plate. Such an arrangement poses problems in properly setting the gap distance and in the expense of providing the apertured insulating plates and the conductive plates of which the electrodes are formed.